A study of Caesarean section and instrumental delivery rates in the maternity hospitals in New Zealand delivering over 1,000 women per year was undertaken. The results at Middlemore Hospital were compared with those seen elsewhere. The Caesarean section rate at Middlemore Hospital in 1993 was significantly lower than the other large maternity hospitals in New Zealand. The Caesarean section rate at Middlemore from 1988 to 1993 has shown a significant downward trend which is different from the trends at other hospitals. The spontaneous vaginal delivery rates at Middlemore Hospital were higher than at other New Zealand hospitals between 1988 and 1993. We conclude that Middlemore Hospital has been successful in maintaining low interventional delivery rates by New Zealand and international standards--the Caesarean section rate remains below 10% and the spontaneous vaginal delivery rate approaches 85%. This is likely to be a consequence of a number of factors operating together but there is evidence to suggest that obstetric management policies at Middlemore do play a role in this.